Jump to content

High oil pressure


Bhaynes85
 Share

Recommended Posts

Have a 1998 Prostar 190 350 gm motor. The oil pressure has been running Very high like 60psi at idle and 80 when on the throttle. Oil and filter have been changed recently. Just bought the boat and have only had it out 3 times and every time the oil pressure gets higher. Dropped it off at the mechanic and he said it looks to have 1 to 1.5 extra quarts of oil in the motor. Is this enough to explain the problem or could it be a more ominous problem?? Thanks for all the help mastercraft team talk has yielded no help
Link to comment
Share on other sites

  • Baller

First, I would wonder about the oil pressure gauge. Next, if there is really that much extra oil in the motor, I would be concerned about fuel dilution (gasoline getting into the oil). Change the oil immediately and see if it happens again. I don't know for sure, but I doubt that extra oil would increase oil pressure?

 

60 psi at idle would not be unusual when the engine is cold. 80 lbs at high RPM may not be disastrous, but you said the pressure is getting higher each time you run it. That is troubling. Still the gauge is the first thing to check (IMHO) and getting the excess oil out needs to be done very soon. I am not a mechanic, just a long time inboard owner. Good luck.

Link to comment
Share on other sites

Will do guys! This forum is really so helpful, I appreciate the help! Are their other things high oil pressure could signal like a bad motor or something disastrous? I just bought the boat and I’m terrified it’s gonna need a new motor, but I’m a glass half full kinda guy!
Link to comment
Share on other sites

  • Baller
Agree- change it first/ get to the correct volume- see what your readings are - step 1. An additional 1.5 is a significant amount and yes could increase pressure, but again get it out and check it with correct volume first. Operating pressure at speed above 60- I’d be checking further for as noted maybe gauge, sending unit etc
Link to comment
Share on other sites

  • Baller

I have a rebuilt 350 in a 210 oil pressure is generally the same psi as yourS when cold it’s a little lower when warm.

Do all that every one recommends check the viscosity of the oil your using if it’s still higher you could go to something lighter.

Worst case scenario you have a stuck spring on your oil pump.

 

 

Link to comment
Share on other sites

  • Baller_

Virtually any modern oil will work in a ski boat. If you run 5W30 and 20W50 in 2 identical engines for 2000 hours or so, it will take full disassembly and measurements to determine any difference in wear. Both will be running the same to the driver and skier.

 

From the above posts, it seems by far your biggest issue is oil dilution (gas getting into the oil). This is not an uncommon occurrence and can cause significant damage if not corrected quickly. Gas is a solvent and will dramatically reduce the lubrication qualities of any oil. Change the oil and filter immediately with whatever quality oil is available and watch the level daily for the next 5 hours or so.

 

If you notice any increase in the oil level, stop using the boat and get it to a good mechanic to correct where the gas is getting in and get a compression or leak down test done to see if any real damage has been done.

If it was easy, they would call it Wakeboarding

Link to comment
Share on other sites

  • Baller
This is a kinda stupid question, and in no way an insult to you, but did you check the oil level immediately after the change: or did you just put in what the "book" called for? Sometimes the stick doesn't match what the book says.
Link to comment
Share on other sites

  • Baller_

There are several places gas can get into oil. One of the more common ones is a rubber diaphragm in the fuel pump that leaks gas into the crankcase. It all depends on the fuel pump if you are susceptible to that problem or not. Could also be a bad valve, bad rings, carburetor dumping in more gas than it can burn or a host of other fairly major issues. Again, change the oil and keep an eagle eye on it for the next few hours.

 

You mentioned that you just bought the boat. Was the oil changed by the previous owner? If you are really lucky, he just overfilled it, but it would be unusual to get 1-1.5 qts extra. Most engines take 4.5-5 qts and oil commonly comes in 5 qt jugs.

 

How many hours on the boat and what is the general condition of the engine? Smooth running, lots of power or cough and sputter, hesitating? Any blue or black smoke out the exhaust or smell of burning oil? Gas in the bilge is not a good sign either.

 

If it was easy, they would call it Wakeboarding

Link to comment
Share on other sites

  • Baller

Gas in the bilge sounds dangerous. There are many places that could leak gas starting at the tank all the way to and including the carb. I am not an expert, but it may be possible that the carb can leak gas into the crankcase even when the boat is not running.

 

On oil, you should read the owner's manual for your engine. My 2015 PCM manual specifies 15w/40 with classification GF-4SM. SN is the updated SM. You are right that 15w/40 is typically diesel oil, and not all diesel oils have either the SM or SN classification. I have been told that the SM or SN makes the oil acceptable for use in gasoline engines.

Link to comment
Share on other sites

@Bruce_Butterfield Yes the previous owner changed the oil. 760 hours. No blue or black exhaust that I have noticed. Runs smooth but a lot less top end than I would expect from such a large motor, I know this could just be my perception!
Link to comment
Share on other sites

  • Baller
Bilge should never have gas. Sounds like you may have some issues that need to be addressed right away. I wouldn't be comfortable taking a boat on the water that's collecting gas in the bilge. Take it to a marine mechanic, make sure to tell the person about the extra oil, seemingly higher pressure, and fuel in the bilge.
Link to comment
Share on other sites

  • Baller

FWIW, 80 PSI is nothing to worry about. 60 PSI cold at idle is very normal.

 

In general, the rule of thumb for MINIMUM oil pressure is 10 PSI/1000 RPM.

 

The way the upper end of oil pressure is set is there is a plunger in the oil pump with a spring behind it that relieves oil pressure once the spring pressure is overcome. There are 4 different kind of oil pumps: Normal, High Volume, High Pressure, and HV/HP. In order to get high volume they increase the size (height) of the oil pump rotor. Not sure if any marine builders are putting HV pumps in their engines, that's usually used to overcome looser tolerances in the crank bearings in race engines. Then there are high pressure pumps. They increase the spring pressure in the plunger. These are used for very high RPM engines that need more pressure at higher RPMs.

 

Normal oil pumps have their pressure cut off set around 70 PSI. When the engine is cold sometimes the blowoff plunger can't flow enough oil with thicker oil and you'll see 80 PSI at speed. This isn't a problem normally. If you start getting over 80, that might indicate a problem.

 

For more info on this, look here:

 

https://help.summitracing.com/app/answers/detail/a_id/4825/~/do-i-need-a-high-volume-or-high-pressure-oil-pump%3F

 

BTW, I would

 

1) Figure out if your oil pressure gauge is accurate. Most are not.

2) Be much more concerned if the amount of "oil" in the crank case is growing. That is usually fuel getting in there, or water if the oil is milky. Or maybe the oil was overfilled when the oil was changed.

 

 

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...